triangular

triangular — adjective

1. having the shape of a triangle, with three straight sides and three corners.

1.adjectiveB1
Definition

having the shape of a triangle, with three straight sides and three corners.

Example

The garden has a triangular flower bed in one corner.

attributive use: triangular + noun

Xiu cut the sandwich into triangular pieces for the children.

Common collocations
  • triangular piece
  • triangular shape
  • triangular building
  • triangular area
  • triangular window
  • triangular block
Synonyms
  • three-sided

    less common; focuses on the number of sides rather than the overall shape

  • wedge-shaped

    used when the triangle is long and narrow, like a wedge

Antonyms
  • round

    a completely different shape with no corners

  • circular

    shaped like a circle rather than a triangle

Grammar Patterns

triangular + noun

be + triangular

Common Mistakes

The table is triangle.
The table is triangular.
'triangle' is a noun; 'triangular' is the adjective form that describes something shaped like a triangle.

2. involving three people, groups, or things that are connected to each other in so

2.adjectiveB2
Definition

involving three people, groups, or things that are connected to each other in some way — for example, a business arrangement among three companies, or a romantic situation among three people.

Example

The two companies formed a triangular partnership with a local supplier in Vietnam.

collocation: triangular partnership

The film explores a complex triangular relationship between a painter, a musician, and a writer.

collocation: triangular relationship

Common collocations
  • triangular relationship
  • triangular partnership
  • triangular trade
  • triangular arrangement
  • triangular alliance
  • triangular cooperation
Synonyms
  • three-way

    more informal; common in everyday speech about relationships or agreements

  • tripartite

    formal; used mainly in law, politics, and business documents

  • trilateral

    used especially for agreements or discussions involving three countries or large organizations

Antonyms

Grammar Patterns

triangular + abstract noun (relationship, arrangement, trade)

Usage Note

Most common in attributive position before abstract nouns such as relationship, partnership, arrangement, alliance, or trade. Unlike sense 1, this sense is rarely used predicatively.

Common Mistakes

They had a triangle relationship.
They had a triangular relationship.
'triangle' is a noun, not an adjective; use 'triangular' to describe the relationship.

Word family

  • triangle
    nounA2
  • triangulate
    verbC1
  • triangulation
    nounC1

Synonym discussion

Sense: adjective/1

All three words describe a shape with three sides, but they differ in precision and use. Triangular is the general-purpose term for anything with the shape of a triangle — it works for flags, roofs, plots of land, and abstract diagrams. Three-sided focuses strictly on the count of sides rather than the overall form; it is less common and sounds more technical or geometric, as in 'a three-sided polygon.' Wedge-shaped describes a thick, narrow triangle that tapers to a point, like a slice of pie or a doorstop. Use triangular in everyday descriptions ('a triangular banner'), three-sided when counting sides matters ('a three-sided enclosure'), and wedge-shaped when the object is long and pointed ('a wedge-shaped piece of cheese').

triangular ↗three-sidedwedge-shaped

Common collocations

Adverbs

  • roughly triangular
  • almost triangular
  • perfectly triangular
  • roughly triangular

Phrases

  • in a triangular shape
  • triangular in form

Etymology

LatinFrenchEnglish

Triangular comes from Latin 'triangulus,' which was made up of 'tri-' meaning 'three' and 'angulus' meaning 'corner.' The word was modified in French before passing into English around the 1500s. The shape meaning appeared first; the broader sense of 'involving three parties' developed later, by the 1800s.